Rozhen Observation Calendar

Which nights are best for a target over the coming weeks. The astronomy mark (darkness × altitude × Moon) is computed for every night; the weather and the overall mark exist only where Open-Meteo has a forecast (the next four days) or ERA5 history (past nights) — the rest is honestly blank.

Best nights for HD 189733: 03-16 (34), 03-17 (34), 03-18 (33), 03-14 (32), 03-15 (32) — by astronomy; check the weather when the night is within four days.

2027-02-21astronomy score per night — click a bar for that night2027-03-22

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-02-21 Sun	11	—	unknown	05:25–05:35 (good, 0.17 h)	71.1° 10:15	10.01	99%	127.9°
2027-02-22 Mon	12	—	unknown	05:20–05:35 (good, 0.25 h)	71.1° 10:10	9.97	95%	119.9°
2027-02-23 Tue	12	—	unknown	05:20–05:35 (good, 0.25 h)	71.1° 10:05	9.92	89%	110.8°
2027-02-24 Wed	12	—	unknown	05:20–05:35 (good, 0.25 h)	71.1° 10:05	9.88	81%	101.3°
2027-02-25 Thu	12	—	unknown	05:15–05:30 (good, 0.25 h)	71.1° 10:00	9.84	72%	91.9°
2027-02-26 Fri	13	—	unknown	05:10–05:30 (good, 0.33 h)	71.1° 09:55	9.79	62%	82.6°
2027-02-27 Sat	14	—	unknown	05:05–05:30 (good, 0.42 h)	71.1° 09:50	9.75	53%	73.8°
2027-02-28 Sun	15	—	unknown	05:00–05:25 (good, 0.42 h)	71.1° 09:45	9.7	43%	65.6°
2027-03-01 Mon	16	—	unknown	04:55–05:25 (good, 0.5 h)	71.1° 09:45	9.66	34%	58.1°
2027-03-02 Tue	19	—	unknown	04:45–05:25 (good, 0.67 h)	71.1° 09:40	9.61	25%	51.6°
2027-03-03 Wed	22	—	unknown	04:35–05:20 (good, 0.75 h)	71.1° 09:35	9.57	18%	46.6°
2027-03-04 Thu	24	—	unknown	04:30–05:20 (good, 0.83 h)	71.1° 09:30	9.52	11%	43.6°
2027-03-05 Fri	25	—	unknown	04:25–05:20 (good, 0.92 h)	71.1° 09:30	9.47	6%	43.2°
2027-03-06 Sat	25	—	unknown	04:25–05:15 (good, 0.83 h)	71.1° 09:25	9.43	2%	45.4°
2027-03-07 Sun	26	—	unknown	04:20–05:15 (good, 0.92 h)	71.1° 09:20	9.38	0%	50.0°
2027-03-08 Mon	27	—	unknown	04:15–05:15 (good, 1.0 h)	71.1° 09:15	9.33	0%	56.5°
2027-03-09 Tue	27	—	unknown	04:10–05:10 (good, 1.0 h)	71.1° 09:10	9.28	3%	64.4°
2027-03-10 Wed	29	—	unknown	04:05–05:10 (good, 1.08 h)	71.1° 09:10	9.23	7%	73.3°
2027-03-11 Thu	30	—	unknown	04:05–05:10 (good, 1.08 h)	71.1° 09:05	9.19	13%	82.7°
2027-03-12 Fri	30	—	unknown	04:00–05:05 (good, 1.08 h)	71.1° 09:00	9.14	21%	92.5°
2027-03-13 Sat	31	—	unknown	03:55–05:05 (good, 1.17 h)	71.1° 08:55	9.09	31%	102.4°
2027-03-14 Sun	32	—	unknown	03:50–05:05 (good, 1.25 h)	71.1° 08:50	9.04	42%	112.0°
2027-03-15 Mon	32	—	unknown	03:45–05:00 (good, 1.25 h)	71.1° 08:50	8.99	53%	121.0°
2027-03-16 Tue	34	—	unknown	03:45–05:00 (good, 1.25 h)	71.1° 08:45	8.94	64%	128.8°
2027-03-17 Wed	34	—	unknown	03:45–05:00 (good, 1.25 h)	71.1° 08:40	8.89	75%	134.5°
2027-03-18 Thu	33	—	unknown	03:40–04:55 (good, 1.25 h)	71.1° 08:35	8.84	84%	137.0°
2027-03-19 Fri	31	—	unknown	03:40–04:55 (good, 1.25 h)	71.1° 08:35	8.79	92%	135.6°
2027-03-20 Sat	30	—	unknown	03:35–04:55 (good, 1.33 h)	71.1° 08:30	8.73	97%	130.8°
2027-03-21 Sun	30	—	unknown	03:35–04:50 (good, 1.25 h)	71.1° 08:25	8.68	100%	123.5°
2027-03-22 Mon	29	—	unknown	03:35–04:50 (good, 1.25 h)	71.1° 08:20	8.63	100%	114.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-02-21&days=30"
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&days=30&format=csv" -o m31-calendar.csv

One row per night: score_astronomy always, score_weather / score only where a forecast or history exists (null otherwise, with weather_source saying which), best window, dark hours, Moon illumination and separation, transit. 7–60 nights. Errors: 400 with invalid_date or target_unresolved. Results are cached for six hours; calculation version 2026-10-10.1.